Hydrocarbon conversion system



June 24, 1941. M. H. ARvl-:soN

HYDROCARBON CONVERSION SYSTEM 5 Sheets-Sheet l v Filed Dec. 30, 1939INVENToR /lam'lwrp/eswz ATTORNE June 24, 1941. M. H. ARvEsoN HYDROCARBONCONVERSION SYSTEM Filed Dec. so, 1939 3 sheets-sheet 2 M. H. ARVESONHYDROCARBON CONVERSIO SYSTEM l June-24, 1941.

` Filed Dc. 50, 1939 5 Sheets-Sheet 3 Mazzi/Me( jNvENToR Q/D M ATTQRBZYPatented June V24, 1941 mmnocaaon coNvEnsIoN sY-s'rEM i Maurice H.Arveson, Flossmoor, Ill., assignor to Standard Oil Company, Chicago,Ill., a corporation of Indiana Application December 3o, 1939, serial No.311,886

(cl. 19e-52) 16 Claims.

tofore been of two types: (1) the stationary or hxed bed type, and (2)the moving bed or contin` nous type.' The object of my invention is toprovide a new type of catalytic systemwhichwill avoid the disadvantagesof both previous types lwhile retaining advantages of both.

Fixed bed catalyst systems lare exemplied by i,

the so-called Houdry plants wherein nested periorated tubes are imbeddedthroughout the catalyst mass for charging and withdrawing gases andvapors to and from said mass. The cost of such a reactor is enormous andit requires an cxhorbitantly large number of valves most of which mustbe automatically operated. AWhen used for catalytic cracking theon-stream period is only a matter of minutes and the catalyst isregenerated in situ, the regener-ation usually requiring two or 'threetimes as long as the onstream period. `Wide temperature ranges areinvolved in going over from on-stream to regeneration and fromregeneration bach to on-stream periods, thus placing a severe mechanicalstrain on the apparatus structure and :making it im possible to obtainuniform reaction conditions during the on-stream catalytic conversionperiod.

-jcct of my invention is to provide a system which will avoid thediculties hereinabove enumerated and the many other difficultiesk whichare inherent in xed bed catalyst conversion operations.

In moving -bed operationsv the catalyst itself flows through thereaction chamber eitherconcurrent with or countercurrent to the flow ofhydrocarbon vapors undergoing conversion and the spent `catalystmaterial is regenerated outside of the conversion zone and then returnedfor further use. In this system the temperature and lpressure conditionsin the conversion zone are maintained constant, and the conversion iscontinuous under substantially optimum conditions so that maximumproduct quality and maximum yields are obtainable. In such' systems,however, the problem of regulating catalyst flow through the tubes hasnot ybeen and perhaps cannot he satisfactorily-solved. If any particulartube discharges too rapidly or for some other reason is emptied it formsa bypass through which the hydrocarbons flow without coming in contactwith the catalyst material. If catalyst material becomes stagnant thereis a tendency for coke formation and tube plugging which may requireremoving the entire tube. An object of my invention is to avoid theseand the many other inherent disadvantages of continuous or, moving bedcatalyst systems while at the same time retaining the advantages of saidsystems.

A further object of the invention is to provide an 1in-proved catalyticreactor with positive means for renewing catalyst therein (i. e,discharging spent catalyst therefrom and adding fresh catalyst thereto)without interrupting the ow of hydrocarbon vapors through the reactor,without permitting the by--passing of hydrocarbon vapors through emptytubes and without requiring tne regulation of catalyst flow through thetubes. A turtner object is to avoid catalyst abra-n sion anddisintegration which has heretofore been caused by means tor regulatingcatalyst ow; in

other words, it is my obJect to reduce to a minimum the production oi'catalyst rines and the loss o1 catalyst from this and other sources.

A rurtner object is to provide an improved catalytic conversion systemwhich will operate under substantially constant conditions oftemperature and pressure and produce maximum yields oi' high qualitymotor fuel with minimum losses to gas and coke. A further object is toprovide improved means for preventing incoming catalyst from beingfouled -by carbon deposits resulting Irom contact of hydrocarbon vaporswith catalyst prior to the introduction Vof the catalyst into theconversion tubes. A further object is to provide an improved means fordistributing catalyst material in reaction tubes or beds. A furtherobject is to provide improved means .for discharging catalyst `from acatalyst bed while the reactor is onstream. A 'further object is toprovide method and means for completely emptying one section of areactor and then lling that section of the reactor With catalyst withoutdisturbing other catalyst sections and Without permitting anyappreciable flow of gases or vapors through the tube during the emptyingstep, while empty, and during the filling step. Other objects of theinvention will be more fully understood as the following detaileddescription thereof proceeds.

I have discovered that the advantages of moving bed catalyst systems maybe obtained without the inherent disadvantages of said systems bydispensing entirely with the regulating means heretofore employed forcontrolling the rate of catalyst flow through the reactor, stopping thevapor flow through each tube when the catalyst therein becomes spent,completely discharging the catalyst therefrom Without permitting vaporflow therethrough, filling the tube with fresh catalyst while it remainseffectively cut out of the system and then passing hydrocarbons throughthe tube until the catalyst therein becomes spent once more.

Although the invention is subject to various forms and modifications Iprefer to employ a cylindrical chamber provided with a plurality ofcatalyst tubes or sectors which may be surrounded by a heat exchangemedium. A rotating upper member seals the ends of the tubes which arebeing emptied, charges fresh catalyst into the empty tube sector or celland prevents the introduced hydrocarbons from contacting freshlyintroduced catalyst prior to the actual placement of the catalyst in thetubes. A lower rotating member holds the catalyst in those tubes throughwhich'hydrocarbon vapors are beingpassed, permits the discharge ofcatalyst materials which have become spent, and seals the lower ends ofthe tubes which are empty or which are being filled with catalystmaterial. These upper and lower members are rotated in unison eithercontinuously or intermittently so that the catalyst in each tube ison-stream for a time sufficient for its maximum effectiveness, thencompletely emptied of spent catalyst material, recharged with freshcatalyst material and returned to on-stream position. The invention willbe more readily understood from the following detailed description readin conjunction with the accompanying drawings wherein similar parts aredesignated by like reference characters in the several figures andwherein,

Figure 1 is a vertical cross section of a simplified form of my improvedcatalytic reactor shown in conjunction with a schematic flow diagram oflother parts of the conversion system;

Figure 2 is an enlarged vertical section of the reactor shown in Figure1;

Figure 3 is a horizontal cross section taken along 'the line 3-3 ofFigure 2;

Figure 4 is a cross section through the reactorv taken along the line4-4 of Figure 2;

Figure 5 is a detail cross section of the grating nlustrated in Figure4;

Figure 6 is a section taken along the line 4,-4 of Figure 2 showing amodified lower plate structure for use with hinged screens;

Figure 7 is a detail section taken along the lines 1-1 of Figure 6;

Figure 8 is a detail section taken along the lines 8-8 of Figure 6;

Figure 9 is a detail section taken along the lines 9-9 of Figure 6;

Figure 10 is a detail section taken along the lines III-I0 of Figure 6;

Figure 1l is a detail section taken along the lines II-II of Figure 6;

Figure l2 is a detail cross section along the sheet I'I.

Figures 13 and 14 are detail sections similar to Figures 9 and l0wherein a cam surface coacts with a lug on the hinged screen frame forpositioning the latter, and

Figures 15 and 16 show a modification of the structure shown in Figures11 and 12, wherein a vertically movable closure plate is held againstthe lower end of the tubes by pivoted'weights.

While the invention is applicable to innumerable hydrocarbon conversionprocesses it will be described in connection with a catalytic crackingprocess vfor converting gas oil to high quality motor fuel. The catalystfor such a process is preferably of the silica alumina type and it mayconsist essentially of natural clay such as bentonite which has beenacid-treated or otherwise activated to remove objectionable impurities(an example of which is acid-treated bentonite commercially marketed asSuper Filtrol) Alternatively, the catalyst may consist essentially ofsiilca gel with a metal oxide associated therewith or deposited thereon;a preferred catalyst of this type is silica gel having about 15% to 25%of alumina deposited thereon by impregnation, adsorption,coprecipitation or other known means. Oxides of other metals such asthorium, magnesium, copper, nickel, manganese, titanium, beryllium,cerium, zirconium, boron, etc. may be used with or in place of alumina.

For hydrogenation, dehydrogenation, reforming and aromatization thecatalysts are preferably Group VI metal oxides deposited on alumina,although other metal oxides such as vanadium oxide, cerium oxide, etc.may be used. For polymerization the catalyst may consist of kieselguhrimpregnated with phosphoric acid or it may comprise copperpyrophosp-hate on activated carbon. For isomerization or desulfurizationthe catalyst may be bauxite, active alumina, activated clays, etc. Thecatalysts per se form no part of the present invention and they will notbe described in further detail. It should Ibe understood, however, thatany type of catalyst may be used which will effect the desiredconversion and the catalyst may be in granular, molded, pelleted,extruded or any other form. Preferably the catalyst particles are offairly uniform size, although the particle size may range from about 1inch to about 200 mesh.

Referring to Figures 1 and 2 of the drawings, gas oil is forced by pumpI0 through coils II of pipe still I2 and introducedby transfer line I3into the upper part of reactor I4. In this reactor there are a pluralityof substantially vertical tubes I5 with their upper ends welded to tubesheet I6 and their lower ends welded to tube The space in the reactorvessel which is outside of the tubes and which is bounded by 4,tubesheets I6 and I1 may contain any heating fluid such as flue gases, fusedsalts, mercury, diphenyl, etc. introduced through line I8 and withdrawnthrough line I9. 'Ihe temperature of the catalyst in tubes I5 may beabout 800 to 1000 F., preferably about 900 F., and the space velocity ofhydrocarbon vapors through the catalyst tubes is about 0.2 to 4.0,preferably about 1, volumes of charging stock (liquid basis) per volumeof catalyst space per hour. The pressure in the reactor is aboutatmospheric to pounds per square inch, preferably about 25 to 50 poundsper square inch. 'Ihe details of the reactor per are withdrawn throughline 21.

Spent catalyst is withdrawn from the base of reactor it through sealedhopper 28 and returned` by line 29 to any suitable system 30 forstripping hydrocarbons out of the catalyst, re-

generating the spent catalyst and removing oxyl gen from the regeneratedcatalyst. The removal oi hydrocarbons from the catalyst or purging maybe effected by stripping with steam, a hydrocarbon gas or any othersuitable inert gas, or it may be effected by the use of a vacuum. The

Y regeneration may be effected in a burner utilizing recirculated duegas as illustrated in Wilson Patent No. 1,520,493. Preferably theregeneration is effected under a pressure oi about to 125 pounds persquare inch since such pressure lowers the lrindling point of thecarboriaceous material in the catalyst and makes possible the use oilarger amounts of recirculated Yilue gas (for absorbing andwithdrawingthe heat oi regeneration) without unduly increasing thevelocity oi the gases dowing through the regeneration system.Regeneration may likewise be eiiected in a louvered type continuoussystem described and claimed in my copending application Serial No.309,448. Since regeneration per se forms no part ci the presentinvention it will not be described in further detail. The regeneratedcatalyst which is preferably at a temperature of about 850 to 900 F. isreturned by line .ill to seal hopper 32 from which it is introducedintel reactor i4.

Referring more specifically to the reactor structure, the catalyst fromhopper 32 discharges through valved conduit 33 into the rotating feederpipe 3d, the upper part of which is formed into a curved annular ange 35rotating in and closely fitting against the inner curved bearing surfaceof member 36 which may be the lower end oi conduit 33 or a separateelement welded to thetop of chamber I4. Packing material 31, such asasbestos, held by bolted plate 38 helps to maintain the vapor seal andhold curved ange 55 against bearing 36 while permitting the rotation offeeder 34 around a vertical axis.

The lower discharge end of feeder pipe 34 is welded to a rotating diskplate 39 which is centered by central bearing member 40. Plate 39 hasholes 4i under feeder tube 34 through which catalyst may flow fromfeeder pipe 34 into tubes tween the ends of these slots andthe otherside of the juncture withieeder 34, plate 39 is provided withimperiorate portion 45. This portion oi the plate acts as a seal fortube ends during the discharge of spent catalyst from the tubes.

The lower part of rotatable plate 39 is machined to give'a fairly tightfit with the upper ends oi the tubes. This plate is rotated by pinionwheel 46 mounted on shaft 41 extending through packing gland 48 anddriven by beveled gear 49 meshing with beveled gear 50 which in turn isxed to shaft 5I driven by any suitable motor not shown. Idling plnions52 hold the plate in place during its rotation, pinions and 52 meshingwith ring gear or rack 53.

In the position illustrated in Figure 3 and with plate 39 movingcounterclockwise in the direcl tion of the arrow the catalyst materialfrom feeder '34 is viilling the Vtubes through openings 4Iin zone A; thetubes in zone B are empty, the-tubes in zone C are discharging spentcatalyst and the tubes in zone D are on-stream. As the plate continuesto rotate the tubes in zone 4A will go on-stream, the tubes in zoneBwill be iilled, the tubes in zone C* will be in the neutral zone and thenext tubes in succession will be emptied. This operation will be morefully understood after the description of the catalyst discharge means.

Adjacent and bearing against the bottom ot tubes I5 is another rotatableplate 54 (see Figure 4) which is imperforate in zones .A and B, providedwith somewhat horizontal elongated apertures 55 in zone C and providedwith recesses 55 in zone D. The recesses may be in the form of aperturesor annular slots, the preferred structure being a wedge-shaped grating,as indicated'by Figure 5. The function oi these slots, apertures orsimilar structures is to form a support for catalyst material in thetubes and to permit the dow or hydrocarbon vapors from the tubes to thelower part oi the reaction chamber. The wedge-shaped structureillustrated in Figure 5 is effective for preventing the clogging of thegrating structure with catalyst particles.

The outer edge of plate 5t is provided with the beveled gear or annularrack 5l driven by pinion 58 mounted on shaft 59 extending throughpacking gland 50 and carrying a beveled gear 6I meshing with beveledgear 52 keyed to shaft 5i. Idling pinion supports 53 cooperate withpinion 5,8 in supporting plate 54 and holding it in place to maintain aclose fit between the upper part of the plate and the lower ends oitubes I5.

As plate 54 is rotated in the indicated counterclockwise direction itwill be seen that the upper ends of thetubes in zones A and E are sealedwhile the tubes in zone C are discharging spent catalyst throughapertures 55, all ofthe remaining tubes being on-stream withV vaporsflowing through the grating or the annular slots 55. The irnperforate`section of plate 54 which is in zones .A and B seals the lower ends ofthe tubes which are being filled and the tubes which have lust beenemptied. This imperforate section extends for suiiicient area to'preventany overlapping of tubes which are being filled and emptiedrespectively. While the tubes in zone C are being emptied through slots55 the `upper ends of those tubes are sealed by the imperforate portion45 of upper plate 39. Thus all tubes which are not actually on-streamare effectively sealed against the passage of hydrocarbon vaporstherethrough. It will be understood, of course, that plates 35 and 54are rotated together at the same speed, either continuously orintermittently. I prefer to allow suillcient registrationoi? theapertures 55 at the lower ends of the tubes to completely discharge thecatalyst from said tubes but it should be understood that a more rapidrotation of the plates may effect only partial removal of the catalystfrom the tubes.

` To center plate 54 and hold Vit snugly against the lower ends oi tubesI5 I provide shaft 54 ber is illustrated in Figures 6 to'16. inclusive,and

while this form is slightly more complicated than the form hereinabovedescribed it offers the further advantage of preventing abrasion andcatalyst disintegration due to the shearing effect of the rotatinggrating under the catalyst tubes. In this preferred modification theupper plate and catalyst distributing mechanism may be as previouslydescribed, but instead of employing a simplev plate with perforations orgrooves, as illustrated in Figure 4, I employ a hinged screen at thebase of each tube with means for holding these screens snugly againstthe ends of the tubes while the tubes are on-stream, means forpermitting the screens to pivot on their hinge for discharging spentcatalyst and means for sealing the tubes prior to and during thecatalyst charging step.

Referring to Figure 6, I provide a plate 10 which is supported androtated in exactly the same manner as plate 54 hereinabove described.This plate contains an imperforate section 1I illustrated in zones A andB. It contains a plurality of concentric slots 12 which may extendapproximately 270 around the plate and which slots are similar to slots43 and 44 in plate 39. The width of these slots is approximately equalto the inside diameter of the tubes or, more exactly speaking, to theinside diameter of the screen supports as will be hereinafter described.In zone C I increase the width of the slots to make them wider than theoutside diameter of the screen supports, thus providing tube dumpingapertures 13 which are equivalent in function to the apertures 55 ofplate 54.

Referring to Figures 7 to 12, Iprovide each tube I with an annularscreen support 14 which fits snugly against the lower end of the tube.

This annular screen support is secured to one side of hinge 15, theother side of the hinge being secured to tube sheet I1 or to the lowerend of the tube itself by a suitable bracket 16. Annular screen support14 carries a screen or grating 11 for supporting catalyst material intubes I5 while permitting the flow of vapors therethrough.

In zone D the annular screen support 14 is held against the end of tubeI5 by bearing surfaces 18 on plate 10 on both sides of slot 12. Thus asplate rotates in a'counter-clockwise direction there is no abrasion ofcatalyst material against the rotating plate but merely a slidingcontact between the rotating plate and the annular screen support. Whenzone C reaches each particular screen support bearing 18 is discontinuedand the enlarged slot opening permits the screen support to pivotdownwardly on its hinge as shown in Figure 9. Thus in zone C the spentcatalyst may be discharged from the' tube.

As the plate continues to rotate the screen support is forced back intoposition against the lower end of the tube by surface 19 on theimperforate section 1I of plate 10 so that when zones B and A are underthe tubes this imperforate section 1I of plate 10 effectively seals thelower ends of the tubes and prevents gases and vapors from iiowing intoor out of said tubes. This position of the tubes is shown in Figures 11and 12. While the tubes are thus sealed and catalyst screen supports aresupported and sealed by imperforate plate 'section 1I the tubes arerecharged with fresh catalyst as hereinabove described. On continuedrotation of the plate the screen supports are held in place by bearingsurfaces 18 while hydrocarbons pass through the catalyst through slot12.

Instead of supporting the edges of annular screen supports 14 on'bearing surfaces 18 I may make the slots 12 slightly greater in widththan the outside diameter of screen supports 14 and I may provide thescreen supports with lugs 88 as illustrated in Figures 13 to 16. Theselugs slide on bearing surfaces 18 in zone D but in zone C there is acam-like depression 8I in bearing surface 18 which permits the screensupport to pivot on its hinge and discharge spent catalyst.

`Cam surface 82 forces the screen support back against the lower ends ofthe tubes in the saine manner :that inclined surface 19 repositions thescreen supports.

Instead of employing a Y simple imperforate plate section 1I I mayprovide zones A and B with annular slots or recesses 83 provided withannular plates 84 machined to t snugly against the lower surfaces ofannular screen supports 14 and to seal the same. Plates 84 arepreferably provided with inclined surfaces 85 which serve somewhat thesame function as inclined surfaces 19 and 82. These plates may be heldtightly against the annular screen support 14 by means of weights 86mounted on the ends of bars 81 which are pivoted on pins 88 andpivotally connected to the lower part of plates 84 by connection 89. Bymaking the distance between weight 86 and pivot 88 materially longerthan the distance between pivot 88 and connection 89 the desiredleverage may be obtained for exerting sumcient upward pressure againstplate 84 to effectively seal .the lower ends of tubes I5 against boththe Weight of catalyst and pressure.

In all of the modifications hereinabove described it will be seen that Ihave provided means for emptying and refilling tubes in a reactionchamber Without permitting or at least reducing to a very minimum theentrance of hydrocarbon vapors into said tubes during and between saidfilling and emptying steps. It will be noted that I have avoided thenecessity of controlling or regulating the continuous flow of catalystmaterial through the catalyst tubes and at the same time I have obtainedall of the advantages of the continuous moving bed catalyst system. Inthe modiiication described in Figures 6 to 16 I uhave provided means forpreventing catalyst abrasion. In short I have obtained all of theadvantages of continuous operation Without the inherent dimculties ofthat system and at the same time I have obtained the.advantages withoutthe disadvantages of a xed bed catalyst system.

To positively insure against leakage of hydrocarbon vapors into feederpipe 34 or into the sealed hc'ppers, an inert gas may be introducedthereinto Ithrough lines 90, 9|, 92 etc. to maintain the necessarypressure.

My invention is not limited to the particular structure or to theparticular modifications herein disclosed since many alternativestructures and modifications of the invention will be apparent to thoseskilled in the art from the above description. The word tube" or tubesyin the followamasar. 5

ing claims are hereby defined to include not only circular conduits butconduits of any other contou in other words, a tube is a conduit whichmay be alternately iilied -with catalyst at one end and from whichcatalyst may be discharged at the other.

I claim: Y

l. In a catalytic hydrocarbon conversion system comprising a catalyticreaction chamber containing a plurality of tubes adapted to containcatalyst, the method of eiecting continuous operation, which methodcomprises periodically emptying catalyst from at least one of said tubeswhile other of said tubes remain on-stream, charging iresh catalyst intosaid emptied tube while other of said tubes remain ori-stream andpreventing the by-passing of hydrocarbon Va'- pors through said Itubewhile it is empty and while catalyst material is being dischargedtherefrom and charged thereto.

2. The method or effecting continuous catalytic conversion whichcomprises mounting a plurality oi catalyst tubes in a reaction chamber,maintaining certain of said tubes full oi catalyst while other ci saidtubes are being emptied and lilled with catalyst material, preventingthe pas- `sage or vapors through each tube while it is empty and whileit is being emptied and filled, removing spent catalyst material fromthe reaction acne without interrupting the iiow or hydrocarbon vapors insaid cone, and introducing catalyst to said reaction none withoutinterrupting :the ilow oi hydrocarbon vapors in said zone.

3. The process oi claim 2 wherein catalyst introduced into the system iskept out of contact with hydrocarbon vapors until it is positioned insaid tubes.

i. The method of renewing catalyst in one of a plurality oi tubesadapted to contain catalyst without interrupting the flow oihydrocarbons through other of said tubes, which method comprisesenclosing a plurality of tubes in a catalytic reaction chamber, sealingthe top of one of said tubes .and opening the bottom thereof to permitthe discharge of `spent catalyst therefrom' in a catalyst dischargezone, sealing the bottom of said tube while catalyst is vbeingintroduced into the top thereof in a catalyst charging zone and lspacing the discharge zone sufiiciently far from the charging zone toprevent the simultaneous charging and discharging of said catalyst tube.5. The method of claim 4 which includes the further step of maintaininga positive inert gas pressure in the catalyst charging zone suiiicientto prevent leakage of hydrocarbons thereinto.

6. In a catalytic conversion system a catalyst reactor chamber, aplurality of tubes adapted to contain catalyst substantially verticallymounted in said chamber, means for selectively introducing catalyst intothe top of at least one of said tubes while the top of at least one ofsaid tubes is closed and the top of at least one of said tubes is opento the flow of hydrocarbon vapors, means for removing catalyst from thebase of one of said tubes while the top of said tube is closed, meansfor closing the bottom of said tube while it is `being charged withfresh catalyst and means for holding catalyst in the tube whilepermitting' the flow of hydrocarbon vapors therethrough. l

'7. The apparatus of claim 6 which includes means in said reactorchamber for maintaining catalyst out of contact with vapors until saidcatalyst is deposited in said tubes.

3. In a catalytic conversion system a plurality of substantiallyvertical. concentrically arranged tubes adapted to contain catalyst, anupper plate containing an imperforate section, a catalyst distributingsection and a slotted section, a. lower plate containing a catalystdischarge section, a tube sealing'section and a slotted section for thepassage oi hydrocarbon vapors therethrough. means for simultaneouslyrotating both of said plates and for maintaining the imperforate andsealing section oi the upper plate closely against the upper end oi'each tube while it is being emptied and for maintaining the tube sealingsection of the lower plate closely against the lower end of each tubeWhile it is being filled. v

9. In catalytic conversion apparatus a plurality of tubes adapted tocontain catalyst, a closed catalyst chamber surrounding said tubes,screen supports hinged adjacent the lower ends of said tubes, means forperiodically holding said supports against said lower tube ends, means"for periodically moving said holding means out of holding position sothat said hinged supports may swing away from said tube ends, and meansfor periodically sealing said tube ends against the flow of hydrocarbonvapors.

lil. In catalytic conversion apparatus compris ing a closed catalystreaction chamber containing a plurality oi tubes adapted to containcatalyst and an apertured element relatively movable with respect to thelower end ,oi said tubes, means including a movably mounted screensupport at the base ci each tube for, keeping the catalyst out ofcontact with the movable element while the catalyst is on-stream, meansior successively aligning the aperture oi s'aid element with each screensupport so that it may move away from the tube for discharging catalystfrom said tube, and means for moving the screen support back to itsoriginal position after catalyst has been discharged from said tube.

1l. The apparatus of claim 10 which includes means for sealing the lowerends ci the tubes after catalyst has been discharged therefrom.

12. In catalytic conversion apparatus, a reactor chamber, a plurality oftubes adapted to contain catalyst therein, means for continuouslyintroducing hot vapors into the reactor chamber and withdrawing reactionproducts therefrom, means for introducing catalyst vmaterial into saidchamber without interrupting the conversion therein while preventing theescape of vapors through the catalyst inlet, means for maintaining thetop of each tube closed while said tube is being emptied, means formaintaining at least one end of each tube closed While the tube isempty, means for maintaining the bottom of each tube closed while thetube is being filled, means for holding the catalyst in each tube whilevapors are passed therethrough, and means for removing spent catalystfrom the reactor chamber while preventing the escape of gas therewith.

13. The apparatus of claim 12 wherein the means for maintaining at leastone end oi the tube ends .closed comprises an imperforate portion of arotatable plate.

14. The apparatus of claim l2 wherein the means for maintaining at leastone of the tube contain .catalyst in said chamber, means for l vaporsthrough the tube which is being discharged, means for withdrawing spentcatalyst from the reaction chamber without permitting f the escape ofsubstantial amounts of hydrocarbon vapors, and means for introducingcatalyst to the reaction chamber without permitting the escape ofsubstantial amounts or hydrocarbon vapors at the point of catalystintroduction.

16. In catalytic conversion apparatus, a catalytic reaction chamber, aplurality of tubes adapted to contain catalyst in said reaction chamber,closure means at the -top and bottom of said tubes and means foroperating said closure means whereby each tube is closed at its lowerend while catalyst is being charged thereto, each tube is closedl at itsupper end when catalyst is discharged therefrom and each tube is open atboth ends for the passage of hydrocarbon vapors therethrough while thetube is on-stream.

MAURICE H. ARVESON.

